The plan is a middle way between full nationalisation, as with Northern Rock and Bradford & Bingley banks, and further loans, and echoes a similar operation by the Swedish government during its banking crisis in the 1990s, they said.
Darling hinted at the plan in a BBC interview Sunday, saying he was prepared to take some "pretty big steps that we wouldn't take in ordinary times".
The leader of the main opposition Conservatives, David Cameron, signalled support for the plan, which would offer taxpayers a chance of a return on their investment when banks improve.
Darling is expected to make a statement to lawmakers Monday when parliament resumes after its summer break, where he may also set out Britain's response to Germany's offer of a blanket guarantee to all bank savings.
The announcement Sunday by Chancellor Angela Merkel reportedly sparked anger in London, coming the day after she met with the leaders of France, Britain and Italy in an emergency summit in Paris Saturday to dis